| Message ID | 1377596268-31552-8-git-send-email-tangchen@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | Not Applicable, archived |
| Headers | show |
On Tue, 2013-08-27 at 17:37 +0800, Tang Chen wrote: > memblock_alloc_base_nid() is a common API of memblock. And it calls > memblock_find_in_range_node() with %start = 0, which means it has no > limit for the lowest address by default. > > memblock_find_in_range_node(0, max_addr, size, align, nid); > > Since we introduced current_limit_low to memblock, if we have no limit > for the lowest address or we are not sure, we should pass > MEMBLOCK_ALLOC_ACCESSIBLE to %start so that it will be limited by the > default low limit. > > dma_contiguous_reserve() and setup_log_buf() will eventually call > memblock_alloc_base_nid() to allocate memory. So if the allocation order > is from low to high, they will allocate memory from the lowest limit > to higher memory. This requires the callers to use MEMBLOCK_ALLOC_ACCESSIBLE instead of 0. Is there a good way to make sure that all callers will follow this rule going forward? Perhaps, memblock_find_in_range_node() should emit some message if 0 is passed when current_order is low to high and the boot option is specified? Similarly, I wonder if we should have a check to the allocation size to make sure that all allocations will stay small in this case. Thanks, -Toshi > > Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com> > Reviewed-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> > --- > mm/memblock.c | 3 ++- > 1 files changed, 2 insertions(+), 1 deletions(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index 961d4a5..be8c4d1 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -851,7 +851,8 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size, > /* align @size to avoid excessive fragmentation on reserved array */ > size = round_up(size, align); > > - found = memblock_find_in_range_node(0, max_addr, size, align, nid); > + found = memblock_find_in_range_node(MEMBLOCK_ALLOC_ACCESSIBLE, > + max_addr, size, align, nid); > if (found && !memblock_reserve(found, size)) > return found; > -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 09/04/2013 08:37 AM, Toshi Kani wrote: > On Tue, 2013-08-27 at 17:37 +0800, Tang Chen wrote: >> memblock_alloc_base_nid() is a common API of memblock. And it calls >> memblock_find_in_range_node() with %start = 0, which means it has no >> limit for the lowest address by default. >> >> memblock_find_in_range_node(0, max_addr, size, align, nid); >> >> Since we introduced current_limit_low to memblock, if we have no limit >> for the lowest address or we are not sure, we should pass >> MEMBLOCK_ALLOC_ACCESSIBLE to %start so that it will be limited by the >> default low limit. >> >> dma_contiguous_reserve() and setup_log_buf() will eventually call >> memblock_alloc_base_nid() to allocate memory. So if the allocation order >> is from low to high, they will allocate memory from the lowest limit >> to higher memory. > > This requires the callers to use MEMBLOCK_ALLOC_ACCESSIBLE instead of 0. > Is there a good way to make sure that all callers will follow this rule > going forward? Perhaps, memblock_find_in_range_node() should emit some > message if 0 is passed when current_order is low to high and the boot > option is specified? How about set this as the default rule: When using from low to high order, always allocate memory from current_limit_low. So far, I think only movablenode boot option will use this order. > > Similarly, I wonder if we should have a check to the allocation size to > make sure that all allocations will stay small in this case. > We can check the size. But what is the stragety after we found that the size is too large ? Do we refuse to allocate memory ? I don't think so. I think only relocate_initrd() and reserve_crachkernel() could allocate large memory. reserve_crachkernel() is easy to reorder, but reordering relocate_initrd() is difficult because acpi_initrd_override() need to access to it with va. I think on most servers, we don't need to do relocate_initrd(). initrd will be loaded to mapped memory in normal situation. Can we just leave it there ? Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, 2013-09-04 at 10:05 +0800, Tang Chen wrote: > On 09/04/2013 08:37 AM, Toshi Kani wrote: > > On Tue, 2013-08-27 at 17:37 +0800, Tang Chen wrote: > >> memblock_alloc_base_nid() is a common API of memblock. And it calls > >> memblock_find_in_range_node() with %start = 0, which means it has no > >> limit for the lowest address by default. > >> > >> memblock_find_in_range_node(0, max_addr, size, align, nid); > >> > >> Since we introduced current_limit_low to memblock, if we have no limit > >> for the lowest address or we are not sure, we should pass > >> MEMBLOCK_ALLOC_ACCESSIBLE to %start so that it will be limited by the > >> default low limit. > >> > >> dma_contiguous_reserve() and setup_log_buf() will eventually call > >> memblock_alloc_base_nid() to allocate memory. So if the allocation order > >> is from low to high, they will allocate memory from the lowest limit > >> to higher memory. > > > > This requires the callers to use MEMBLOCK_ALLOC_ACCESSIBLE instead of 0. > > Is there a good way to make sure that all callers will follow this rule > > going forward? Perhaps, memblock_find_in_range_node() should emit some > > message if 0 is passed when current_order is low to high and the boot > > option is specified? > > How about set this as the default rule: > > When using from low to high order, always allocate memory from > current_limit_low. > > So far, I think only movablenode boot option will use this order. Sounds good to me. > > Similarly, I wonder if we should have a check to the allocation size to > > make sure that all allocations will stay small in this case. > > > > We can check the size. But what is the stragety after we found that the > size > is too large ? Do we refuse to allocate memory ? I don't think so. We can just add a log message. No need to fail. > I think only relocate_initrd() and reserve_crachkernel() could allocate > large > memory. reserve_crachkernel() is easy to reorder, but reordering > relocate_initrd() > is difficult because acpi_initrd_override() need to access to it with va. > > I think on most servers, we don't need to do relocate_initrd(). initrd > will be > loaded to mapped memory in normal situation. Can we just leave it there ? Since this approach relies on the assumption that all allocations are small enough, it would be nice to have a way to verify if it remains true. How about we measure a total amount of allocations while the order is low to high, and log it when switched to high to low? This way, we can easily monitor the usage. Thanks, -Toshi -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/mm/memblock.c b/mm/memblock.c index 961d4a5..be8c4d1 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -851,7 +851,8 @@ static phys_addr_t __init memblock_alloc_base_nid(phys_addr_t size, /* align @size to avoid excessive fragmentation on reserved array */ size = round_up(size, align); - found = memblock_find_in_range_node(0, max_addr, size, align, nid); + found = memblock_find_in_range_node(MEMBLOCK_ALLOC_ACCESSIBLE, + max_addr, size, align, nid); if (found && !memblock_reserve(found, size)) return found;